The present invention relates to a novel extract obtained by extraction of the pericarp of Zanthoxylum bungeanum with carbon dioxide and to the pharmaceutical and cosmetic formulations containing it. This extract has anti-inflammatory and analgesic activities and can be used for the treatment of itching.
Pericarp of Zanthoxylum bungeanum is commonly used in China in spices for seasoning food. Moreover, in Chinese and Indian folk medicine, this part of the plant is used as local anesthetic and for the treatment of dysentery. The essential oil, which contains a series of monoterpenes such as 1,8-cimol, linalool, 4-terpinol, caryophyllene, limonene and the like, is also reported as a strong repellent against insects.
Recently, EP 568001 disclosed the antiviral activity of the skin of this fruit. In U.S. Pat. No. 5,137,912, chelcrythrine extracted from the root bark of Zanthoxylum simulans (synonym of bungeanum) was disclosed to be active in the prevention of thrombosis. According to JP 01294657, the extraction of the pericarp with organic solvents provides an extract containing isobutylamides that exerts a local anesthetic effect 30 seconds after application on the tongue and lasting up to 20-80 minutes.
Despite this, there remains a need for additional anti-inflammatory and analgesic formulations, and the present invention satisfies this need.
It has now surprisingly been found that the extract of the pericarp of Zanthoxylum bungeanum, prepared by extraction with carbon dioxide under supercritical conditions, has remarkable analgesic activity without exerting the local anesthetic activity characteristic of the extracts obtained by solvent means. The product of the present invention is prepared by extracting the pericarp of Zanthoxylurn bungeanum, finely ground or transformed into pellets, with carbon dioxide under pressure conditions ranging from 150 to 300 bars, preferably under 180-230 bars, at temperatures ranging from 35 to 55xc2x0 C., preferably at 35-40xc2x0 C.
The resulting extract can either be used as it is, after removing the extraction water, or it can further be purified by partitioning it with immiscible solvents such as aliphatic alcohols and aliphatic hydrocarbons, preferably n-hexane or petroleum ether.
The resulting extracts proved to exert a marked analgesic activity when applied percutaneously to humans; therefore they are valuable for use both in the pharmaceutical and cosmetic fields.
In the pharmaceutical field, these extracts are useful for alleviating pain resulting from diabetic microangiopathy, hemorrhoids, burns, or due to any other local causes. A further application of the extracts of the invention is in the treatment of itching.
In the cosmetic field, the extracts according to the invention are useful in depilatory creams, after-sun formulations, shaving lotions and creams, and in all types of skin treatments requiring local analgesic or anti-itching action.